An annual to short-lived perennial of mudflats and saltmarsh pools, occurring as scattered plants or in dense swards. Reproduction by seed occurs, but plants spread mostly by stolons. Lowland.
This species was first recorded in 1897 in Glamorgan, but colonies in S. Wales had probably died out by the 1940s. It was not found in N. Wales until 1921. It can be locally abundant, but numbers fluctuate markedly annually. It has been suggested that it might be a recent arrival, or even a ballast-alien (Jones, 1991), but the evidence for this is inconclusive.
Oceanic Boreo-temperate element; in Europe restricted to Wales, but widespread in coastal regions of eastern N. America.
Light (Ellenberg): 7
Moisture (Ellenberg): 9
Reaction (Ellenberg): 7
Nitrogen (Ellenberg): 4
Salt Tolerance (Ellenberg): 1
January Mean Temperature (Celsius): 4.2
July Mean Temperature (Celsius): 14.7
Annual Precipitation (mm): 1608
Count of 10km squares in Great Britain: 6
Count of 10km squares in Ireland: 0
Count of 10km squares in the Channel Isles: 0
RDB Species Accounts
Limosella australis R.Br. (Scrophulariaceae)
Welsh mudwort, Lleidlys Cymreig
Status in Britain: VULNERABLE. WCA Schedule 8.
Status in Europe: Vulnerable. Occurs only in Britain.
The major population centres for L. australis are now at the mouths of the Glaslyn and Dysynni rivers (Caernarvonshire and Merioneth), where it is dominant along several 100 metre stretches of river margin, and widespread in the Glaslyn over mudflats and saltmarsh pools. On the lower saltmarsh, L. australis is scattered and loosely spreading, occurring with sparse Juncus gerardii, Suaeda maritima, Triglochin maritimum and other halophytes. By contrast, in upper saltmarsh pools, and conspicuously between sheltered Schoenoplectus tabernaemontani stands, it forms a dense smothering 'turf'. In Britain, the species usually occurs in only a narrow range of salinity conditions, between the dominance of Juncus maritimus downstream, for instance, and Littorella uniflora or Callitriche species upstream.
The rosette is 1-8 cm across, with roughly cylindrical awl-shaped pale green leaves, shallow fibrous roots and rapidly spreading runners. Its flowers are small (2-3 mm), solitary, and scented when fully open, but are cleistogamous, self-pollinated in the bud underwater. However, most plants, and particularly those submerged in more than 50 cm of water, are vegetative and seem to be at least short-lived perennials.
The first record in Britain for the species was from Glamorgan in 1897 (when it was thought to be a form of L. aquatica), and plants were not found in the Glaslyn until 1921, and in the Dysynni since 1955. The new 1990 record for the Dwyryd adds to the current picture of mobility. It is sometimes abundant, but is apparently sensitive to habitat change, which can cause large annual fluctuations in population size. There are also smaller populations on the neighbouring Dwyryd estuary, and records of other, perhaps temporary, colonies on saltmarsh at Morfa Harlech. L. australis used to be found near Port Talbot - in Kenfig Pool, Crymlyn Bog and nearby Morfa Pools - but these populations had probably died out by the 1940s.
L. australis was described originally from Australian material in 1803, and occurs widely throughout the southern hemisphere, north Pacific and eastern North America, but it is unknown from elsewhere in Europe. In Australia, South Africa and Chile it has been recorded far inland, and up to 3,000 metres altitude in New Zealand. The late notice of this quite conspicuous species in Britain, with its fluctuation, mobility, and wide overseas range, indicates a relatively recent arrival. The association with ports and man-made habitats suggests boat traffic, perhaps as a ballast-alien (Jones 1991).
PLANTATT - Attributes of British and Irish plants. (.zip 1455KB) This dataset was compiled and published in 2004, and last updated in November 2008. Download includes an Excel spreadsheet of the attributes, and a PDF explaining the background and nomenclature. Note that the PDF version is the booklet as published, whereas the Excel spreadsheet incorporates subsequent corrections. A hardcopy can be purchased from the Centre for Ecology and Hydrology.
Atlas text references
1986. Atlas of north European vascular plants north of the Tropic of Cancer. 3 vols.
1995. The conservation of scarce and declining plant species in lowland Wales: population genetics, demographic ecology and recommendations for future conservation in 32 species of lowland grassland and related habitats. (Science Report No. 110).
1978. Vergleichende Chorologie der zentraleuropäischen Flora. Volume 2. 2 vols.
1999. British Red Data Books. 1. Vascular plants, edn 3.